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In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains. www.rsc.org/methods Page 1 of 42 Analytical Methods 1 2 3 4 HPLC-LTQ-Orbitrap MSn profiling method to comprehensively characterize 5 6 7 multiple chemical constituents in Xiao-er-qing-jie granules 8 9 Yun Lia, Ying Liub, Rongrong Liua, Siyi Liua, Xiuping Zhanga, Zijian Wangab, Jiayu Zhangb*, 10 11 12 Jianqiu Lub* 13 14 15 16 17 18 19 20 Manuscript 21 22 23 24 25 26 27 28 29 30 31 32 33 34 Accepted 35 36 37 38 39 40 41 42 43 44 45 Methods 46 47 Correspondence to: J. Zhang, Center of Scientific Experiment, Beijing University of Chinese Medicine, Beijing 48 49 100029, China. Tel.: +86 01064287540. E-mail address: [email protected] (J.Y. Zhang). 50 J. Lu, Center of Scientific Experiment, Beijing University of Chinese Medicine, Beijing 100029, China. Tel.: +86 51 01064286203. E-mail address: [email protected] (J. Q. Lu). 52 a 53 School of Chinese Pharmacy, Beijing University of Chinese Medicine, Beijing 100102, China 54 b Center of Scientific Experiment, Beijing University of Chinese Medicine, Beijing 100029, China 55 Abbreviations: HPLC-LTQ-Orbitrap, high performance liquid chromatography coupled with a linear ion 56 57 trap-orbitrap mass spectrometry; XEQJ, Xiao-er-qing-jie granules; TCM, traditional Chinese medicine; ESI, 58 electrospray ionization; CID, collision induced dissociation; FLJ, Flos Lonicerae Japonicae; FF, Forsythiae Fructus; 59 CL, Cortex Lycii; IN, Indigo Naturalis; CARR, Cynanchi Atrati Radix et Rhizoma; RRP, Radix Rehmanniae Analytical 60 Praeparata; PH, Pogostemonis Herba; HRMS, high-resolution mass spectrometry; CE, collision energy; TIC, total ion chromatograms; EIC, extracted ion chromatogram. Analytical Methods Page 2 of 42 1 2 3 4 ABSTRACT 5 6 7 In the present study, a high performance liquid chromatography coupled with a linear ion 8 9 trap-orbitrap mass spectrometry (HPLC-LTQ-Orbitrap) method was developed for a 10 11 12 comprehensive study of the multiple chemical constituents in Xiao-er-qing-jie granules (XEQJ), 13 14 15 which is regularly used as traditional Chinese medicine (TCM) for the treatment of children with 16 17 high fever, sore throat, and lusterless complexion. Seven major categories of constituents 18 19 20 preliminarily isolated from the component herbs were rapidly characterized using Manuscript 21 22 23 HPLC-LTQ-Orbitrap. The fragmentation patterns of these compounds with different skeleton were 24 25 26 clearly elaborated in the electrospray ionization (ESI) collision induced dissociation 27 28 (CID)-MS/MS experiments. Based on the accurate mass measurement (< 5 ppm), MS/MS 29 30 31 fragmentation patterns, diagnostic product ions, and different chromatographic behavior, 91 32 33 34 compounds were unambiguously identified or tentatively characterized, including 33 Accepted 35 36 phenylethanoid glycosides, 13 phenolic acids, 11 flavonoids, 10 alkaloids, 9 ligans, 9 iridoid 37 38 39 glycosides, and 6 saponins. Among them, 2 compounds were potential new ones from Forsythiae 40 41 42 Fructus and 24 were unambiguously confirmed by comparing with their respective reference 43 44 standards. The results demonstrated that our established method was useful and efficient to screen 45 46 Methods 47 and identify targeted constituents from TCM extracts and other organic matter mixtures whose 48 49 50 compounds contained can also be classified into families on the basis of the common carbon 51 52 skeletons. 53 54 55 Keywords: Xiao-er-qing-jie granules; HPLC-LTQ-Orbitrap mass spectrometer; Chemical 56 57 58 constituents; Identification; Fragmentation pathway 59 Analytical 60 Page 3 of 42 Analytical Methods 1 2 3 4 1. Introduction 5 6 7 Xiao-er-qing-jie granules (XEQJ), which is officially listed in the Drug Standard of Ministry of 8 9 Health of the People’s Republic of China, is a regularly used traditional Chinese medicine (TCM) 10 11 12 for the treatment of children with high fever, sore throat, and lusterless complexion.1−2 The recipe 13 14 15 of XEQJ is composed of eight herbal medicines, viz., Flos Lonicerae Japonicae (FLJ) (750g), 16 17 Forsythiae Fructus (FF) (750 g), Cortex Lycii (CL) (750 g), Indigo Naturalis (IN) (250 g), 18 19 20 Cynanchi Atrati Radix et Rhizoma (CARR) (750 g), Radix Rehmanniae Praeparata (RRP) (750 g), Manuscript 21 22 3 23 Pogostemonis Herba (PH) (750 g), and Gypsum Fibrosum (1250 g). 24 25 26 Although the chemical constituents in the component herbs of XEQJ have been intensively 27 28 studied,4−7 little is known about the chemical composition of XEQJ, and few reports are available 29 30 31 on its quality control. For example, Huang et al. determined the contents of chlorogenic acid and 32 33 8 34 phillyrin in XEQJ. These two chemical compositions were from only two herbs, and could not Accepted 35 36 comprehensively control the quality of XEQJ. Therefore, to develop a profiling and reliable 37 38 39 method to screen and characterize the multiple chemical constituents in XEQJ would be an 40 41 42 important step towards further understanding of its pharmacological effects and ultimately quality 43 44 control. 45 46 Methods 47 With the rapid development of high performance liquid chromatography / electrospray 48 49 n 50 ionization tandem mass spectrometry (HPLC/ESI-MS ), it has played an increasingly important 51 52 role in screening and identification of natural products in plant extracts in recent years.9−12 53 54 55 Especially HPLC coupled with high-resolution MS (HPLC/HRMS), which can give exact mass 56 57 58 and has become an extremely powerful tool for characterization phytochemical compounds of 59 Analytical 60 different structure types from complex matrices with its high resolution and best sensitivity, Analytical Methods Page 4 of 42 1 2 3 4 including flavonoids, saponins, phenolic acids, and alkaloids.13−16 For example, the hybrid linear 5 6 n 7 ion trap orbitrap mass spectrometer (LTQ-Orbitrap) combined high trapping capacity and MS 8 9 scanning function of the linear ion trap along with accurate mass measurements within 5 ppm and 10 11 12 a resolving power of up to 100000 over a wider dynamic range compared to many other mass 13 14 17 15 spectrometers. In particular, orbitrap facilitated a fast data-dependent acquisition of accurate 16 17 MSn spectra on a LC timescale, these advantages could be used for increasing the throughput and 18 19 20 identification efficiency of compounds in TCMs. Here, we first systematically reported the Manuscript 21 22 23 structural characterization on the various chemical constituents of XEQJ by using 24 25 26 HPLC-LTQ-Orbitrap MS. First, the collision induced dissociation (CID)-MS/MS fragmentation 27 28 pathways of some certain constituents ever isolated from XEQJ were proposed and then the 29 30 31 diagnostic product ions corresponding to a certain substructure or substituent group were deduced, 32 33 34 which could be applied to the structural characterization of serial compounds that have not Accepted 35 36 reported yet. By comparing the fragmentation patterns, retention time, MSn data with those of the 37 38 39 reference standards and the literatures combining accurate mass measurement, a total of 91 40 41 42 compounds from XEQJ were unambiguously identified or tentatively characterized, which was 43 44 valuable for the quality control of XEQJ. 45 46 Methods 47 2. Experimental 48 49 50 2.1 Materials and chemicals 51 52 Eight reference standards, including rutin, luteoloside, isoquercitrin, lonicerin, calceolarioside B, 53 54 55 isoacteoside, apigetrin, and indirubin, were obtained from the National Institutes for Food and 56 57 58 Drug Control (Beijing, China). Sixteen reference standards of neochlorogenic acid (3-CQA), crypt 59 Analytical 60 chlorogenic acid (4-CQA), chlorogenic acid (5-CQA), sweroside, secoxyloganin, forsythoside A, Page 5 of 42 Analytical Methods 1 2 3 4 forsythoside B, acteoside, kaempferol 3-O-rutinoside, isochlorogenic acid B (3,4-DiCQA), 5 6 7 isochlorogenic acid A (3,5-DiCQA), isochlorogenic acid C (4,5-DiCQA), tricin-7-O-glucoside, 8 9 diosmetin-7-O-glucoside, phillyrin, and macranthoidin A were purchased from Chengdu Biopurify 10 11 12 Phytochemcals CO., Ltd. (Sichuan, China). All these reference compounds showed purities no less 13 14 15 than 98% by HPLC-DAD analysis. FLJ, FF, CL, IN, CARR, RRP, PH, and (XEQJ) were 16 17 purchased from Beijing Tongrentang Medicine Corporation Ltd. (Beijing, China). Material of each 18 19 20 single herb was authenticated by Dr. Jia−Yu Zhang, Center of Scientific Experiment, Beijing Manuscript 21 22 23 University of Chinese Medicine. The voucher specimen was deposited at Center of Scientific 24 25 26 Experiment, Beijing University of Chinese Medicine, China. 27 28 HPLC grade acetonitrile, methanol, and formic acid used were purchased from Fisher 29 30 31 Scientific (Fisher, Fair Lawn, NJ, USA). De-ionized water used throughout the experiment was 32 33 34 purified by Milli-Q system (Millipore, Bedford, MA, USA).